JPH10259844A - Suspension controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized suspension controller capable of maintaining better running stability of an associated vehicle even upon its failure including a short circuit. SOLUTION: If a CPU 12 in a suspension controller finds a mean actual current falling outside the tolerance defined by an estimate current obtained corresponding to a PWM signal, it sets shock absorbers 6 for the wheels of an associated vehicle having clamping force aimed at hard comfortableness during their extension and also that aimed at soft comfortableness during their compression. Even upon a short circuit to cause a rise in temperature of a solenoid 2, the controller controls all the wheels through the absorbers 6 to maintain the total stability of the vehicle and ensure better running stability thereof. Like that way, the controller can ensure better running stability even upon a short circuit through no provision of monitor circuits, which dispenses with monitor circuits and accordingly reduces the size and cost of the controller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension control device for suppressing a swing on a vehicle spring and providing a comfortable ride.

[0002]

2. Description of the Related Art FIG. 14 shows an example of a conventional suspension control device. In FIG. 14, the suspension control device includes a solenoid 2 having one end connected to a battery (power supply) 1 and a movable body (spool) 3 that is displaced in accordance with a current flowing through the solenoid 2 (a current flowing through the solenoid). And a proportional solenoid valve 5 that adjusts the amount of oil fluid 4 that passes according to the displacement of the vehicle, and is provided between the vehicle body (not shown) and the axle (not shown) for each wheel to supply the energizing current, and hence the movable body 3. A variable damping force shock absorber 6 for generating a damping force of a magnitude corresponding to the displacement of the vehicle, an acceleration sensor 7 for detecting the vertical acceleration of the vehicle body, and a controller 8 connected to the other end of the solenoid 2. Approximately.

[0003] The controller 8 has a transistor 10 and a shunt resistor 11 interposed in this order between the other end of the solenoid 2 and the grounding section 9, and turns on and off the transistor 10 to supply current to the solenoid 2. (Conduction current). In this case, the energizing current is composed of a command current and a dither current superimposed on the command current, and the movable body 3 is positioned at a portion corresponding to the command current to generate a desired damping force on the shock absorber 6. At the same time, the movable body 3 is finely vibrated (dithered) at the position according to the dither current, so that the responsiveness of the movable body 3 and thus the damping force of the shock absorber 6 is improved.

The controller 8 further includes an acceleration sensor 7
CPU 1 for obtaining a command current for obtaining a desired damping force and a dither current having a predetermined amplitude in accordance with the detection signal of
2, a dither adjustment circuit 13 for adjusting the amplitude of the dither current output from the CPU 12 as described later, an addition circuit 14 for adding the output signal of the dither adjustment circuit 13 and the command current, and an output value of the addition circuit 14. Shunt resistance 1
And a current feedback circuit 15 that feeds back a terminal voltage value (detection value) of the first terminal to obtain a transistor control signal.
Is supplied to the solenoid 2 by supplying a conduction current in which a dither current is superimposed on a command current.

[0005]

By the way, in the above-described device, a short-circuit failure or a disconnection failure may occur in the solenoid or a harness connected to the solenoid. Then, when a short-circuit fault occurs, there is a problem that an overcurrent may flow into the solenoid and its drive circuit (controller), which may cause damage to each member. When a disconnection failure occurs, the magnitude of the damping force of only the shock absorber on the wheel side corresponding to this failure portion is set to the safe side (for example, the extension side hard / retraction side software). In this case, there is a problem that the stability of the entire vehicle is eventually hindered, and the running stability is impaired.

[0006] In order to solve the above-mentioned problems caused by the short-circuit failure or disconnection failure of the solenoid or the harness, as shown by the two-dot chain line in FIG. 14, the current flowing to the solenoid is detected and the short-circuit of the solenoid or the harness is detected. There is also a conventional example in which a monitor circuit for detecting a failure or disconnection failure is provided upstream of a solenoid. However, in this case, since the monitor circuit is provided separately from the other members, miniaturization of the device is suppressed and the device may be soared.

Further, in the above-described device, regardless of the presence or absence of the monitor circuit, when a large current is supplied to the solenoid for a long time, there is a possibility that the temperature of the solenoid rises abnormally and a short circuit fault is caused. there were.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a suspension control device capable of maintaining good running stability in the event of a short-circuit failure or the like and achieving downsizing of the device. I do. Another object of the present invention is to suppress the passage of a large current when the temperature of the solenoid is high due to a short circuit failure or the like.

[0009]

According to the first aspect of the present invention,
It has a PWM signal generating means having a variable duty ratio for generating a PWM signal, a solenoid connected to a power supply via a switching means which is turned on and off in response to the PWM signal, and a movable body which is displaced in accordance with a current supplied to the solenoid. A proportional solenoid valve, a shock absorber of a variable damping type interposed between the vehicle body and the axle of each wheel so as to extend and contract to generate a damping force according to the displacement of the movable body, and a duty ratio of the PWM signal And a control circuit that obtains the energizing current including dither vibration by switching the current at predetermined time intervals, wherein the control circuit detects an average current of the energizing current,
If the average current deviates by a predetermined value or more compared to the estimated current obtained in response to the WM signal, the duty ratio is set so that the magnitude of the damping force of the shock absorber of each wheel becomes a predetermined value. It is characterized by making it.

According to a second aspect of the present invention, there is provided a PWM signal generating means having a variable duty ratio for generating a PWM signal;
A proportional solenoid valve having a solenoid connected to a power supply via a switching means that is turned on and off in response to a WM signal, and a movable solenoid that is displaced in accordance with a current supplied to the solenoid, and extends and contracts between a vehicle body and an axle of each wheel. A variable damping force type shock absorber that is freely interposed and generates a damping force according to the displacement of the movable body, and the energizing current including dither vibration is obtained by switching a duty ratio of the PWM signal at predetermined time intervals. A suspension control device for detecting an average current of the energizing current, estimating a temperature of the solenoid from an estimated current obtained in response to the PWM signal and the average current, and determining an allowable current from the estimated temperature. A value is obtained, and when the average current exceeds the allowable current value, the PWM signal is decoded so that the average current decreases. And changes the Ti ratios.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A suspension control device according to a first embodiment of the present invention will be described below with reference to FIGS. Note that description of members and portions equivalent to those shown in FIG. 14 will be omitted as appropriate. In FIG. 1, the suspension control device includes a solenoid 2 and a movable body (spool) 3 that is displaced in accordance with a current supplied to the solenoid 2, and adjusts a passage amount of the oil liquid 4 according to the displacement of the movable body 3. A variable damping force type that is interposed between the proportional solenoid valve 5 and a vehicle body (not shown) and an axle (not shown) to generate a damping force having a magnitude corresponding to the energizing current and thus the displacement of the movable body 3. Shock absorber 6, an acceleration sensor 7 for detecting the vertical acceleration of the vehicle body, a battery (power supply) 1 for supplying a current to the solenoid 2 via a transistor (switching means) 16, and a battery 1
And a controller 8 that is interposed between the solenoid 2 and adjusts a current supplied to the solenoid 2.

The controller 8 includes a transistor 16 interposed between the solenoid 2 and the battery 1, a transistor (switching means) 17 connected to a base 16 a of the transistor 16, a transistor 16 and a grounding unit 9. A diode 18 interposed therebetween, a shunt resistor 11 connected to one end of the solenoid 2 and connected in parallel with the diode 18 together with the solenoid 2, a transistor 16 having one end connected to the battery 1 and the other end connected to the battery 1.
A resistor 19 connected to a line connecting the battery 17 and a battery 1
And one end of the resistor 19, and is connected to the transistor 17 via the resistor 20.
And the CPU 12 connected to the line 30 connecting the resistor 11 and the acceleration sensor 7. CPU12 receives the detection data of the acceleration sensor 7 detects a voltage applied V ₀ which battery 1, with so that further inputs the actual current through the line 30,
By performing arithmetic control according to the input data as described below,
Control each member. The CPU 12 has a memory (not shown) and stores a PWM duty ratio-current value map of FIG. 4 described later.

The operation of the thus configured suspension control device will be described below together with the contents of the arithmetic processing of the controller. As shown in FIG. 2, first, initialization is performed (step S1), and determination as to whether or not the control cycle t _{ms has} elapsed is made until YES is determined (step S2). If YES is determined in step S2, the solenoid 2 is driven based on the signal calculated in the previous control cycle (step S3).
Subsequent to step S3, output is performed to members and portions (eg, LEDs) other than the solenoid 2 (step S4).

In the next step S5, the detection values of the acceleration sensor 7 and the like are input. In a succeeding step S6, based on the detection value of the acceleration sensor 7 read in the step S5, a damping force necessary for damping the vehicle body and a command current (estimated current) as a target current necessary for generating the damping force are generated. ).
In the following step S7, the PWM used in step S3 is used.
The duty ratio of the signal is determined. At step S8 following step S7, the duty ratio PW of the duty ratio determined at step S7
A command current (estimated current) including a dither current estimated to be supplied to the solenoid by calculation in accordance with the M signal;
An average current (actual current) obtained from the current input through the line 30 as described later is compared with each other. If the average current deviates from the estimated current by a predetermined value or more, it is determined that a failure state has occurred (solenoid Perform a failure determination).

In the determination of the duty ratio in step S7, a reference duty ratio is obtained from the command current obtained in step S5,
Thereafter, the process is performed by obtaining the rising duty ratio and the falling duty ratio from the map of FIG. 4 stored in the memory of the CPU 12 in advance.

Here, a description will be given of the PWM duty ratio-current value characteristic of FIG. 4 and the energizing current including the dither vibration of FIG. In FIG. 4, reference symbol E denotes a reference duty ratio characteristic line indicating a reference duty ratio, which is a predetermined value of the reference duty ratio without changing the duty ratio of the PWM signal.
_The case where A% corresponding to ₁ is taken as an example. ), The obtained energizing current is obtained by superimposing a high-frequency component around a current I ₁ (average current) having a certain magnitude as shown in FIG. ) Is supplied to the solenoid to obtain a desired damping force.

The rising duty ratio characteristic line F and the falling duty ratio characteristic line G indicating the rising duty ratio and the falling duty ratio, respectively, are below the reference duty ratio characteristic line E, as shown in FIG. The upper side is required to be substantially along the characteristic line E. Further, since the maximum value of the rising duty ratio is 100% and the minimum value of the falling duty ratio is 0%, the rising duty ratio characteristic line F and the falling duty ratio characteristic line G have a portion indicating 100% ( In this case, the current I ₃ [I ₃ > I ₁ ] or more, and the portion showing 0% (in this case, the current I ₂ [I ₂ <
I ₁ ] The following portion) is parallel to the vertical axis.

The rising and falling duty ratios are obtained by adding or subtracting the dither width duty ratio to or from the reference duty ratio as shown in the following equations (1) and (2). (Rising duty ratio) = (reference duty ratio) + (dither width duty ratio) (1) (falling duty ratio) = (reference duty ratio) − (dither width duty ratio) (2)

As is apparent from equations (1) and (2), the magnitude of the dither amplitude can be changed by changing the dither width duty ratio. For example, when outputting a certain current value (average current) I ₁ is first calculated the A% reference duty ratio from the map of FIG. 4, the increase duty ratio B% by adding the dither width duty ratio to the value,
Further, the falling duty ratio C% is obtained by subtracting the dither width duty ratio. Then, the rising duty ratio is output for a predetermined time (1/2 of one cycle of dither vibration) T ₀ , and thereafter, the falling duty ratio is output for a predetermined time T _0. By alternately outputting the ratio every predetermined time T ₀ , FIG.
As shown in, increasing the amplitude determined by the lowering the duty ratio (hereinafter, for convenience, referred to dither amplitude.) So that the electric current that includes the dither vibration cycle at twice the predetermined time T ₀ is obtained . In the present embodiment, the supplied current obtained as described above with reference to FIG. 4 becomes the estimated current, and is used for comparison with an average current (actual current) described later (step S8).

Next, the solenoid driving subroutine of step S3 will be described with reference to FIG. This solenoid drive is performed by an interrupt operation executed every 1/2 hour of the dither cycle. In FIG. 3, first, it is determined whether or not the rising flag is 1 (step S11). If YES is determined in step S11 (up flag = 1), the actual current is obtained by performing A / D conversion of the down current (current at the down duty ratio) (step S12). After that (at the time of the next interruption), a PWM signal having a rising duty ratio is output (step S13), and the rising flag is cleared (step S13).
S14).

On the other hand, if NO is determined in step S11 (rising flag # 1), the actual current is obtained by performing A / D conversion of the rising current (current at the rising duty ratio) (step S1).
Five ). Thereafter (during the next control cycle), a PWM signal having a decreasing duty ratio is output (step S16), and an ascending flag is set (step S17). Subsequent to the processing of step S14 or step S17, an average current (actual current) of the rising current (actual current) and the descending current (actual current) obtained in steps S12 and S15 is calculated (step S18).
It waits for the comparison described later.

Next, the solenoid failure determination in step S7 will be described. FIG. 6 shows the correspondence between the PWM duty ratio and the average current using the voltage and the ambient temperature as parameters. The actual current with respect to the PWM duty ratio increases as the temperature is lower and the voltage is higher.
It becomes maximum (indicated by the solid line G ₁₎ at 0 ° C.. Further, the higher the temperature and the lower the voltage, the smaller the current value becomes, for example, 9 V, 10
It becomes minimum (indicated by the solid line G ₂₎ at 0 ° C.. Under the conditions of the current (estimated current) with respect to the PWM output, the battery voltage of 9 to 16 V, and the solenoid temperature of −30 ° C. to 100 ° C., the solid line G ₁ to
Range of the solid line G ₂ should contains (hereinafter, referred to as the allowable range G _0.) To (are in a state which is not separated by more than a predetermined value). In other words, the average current is not within the allowable range G ₀ is a mean that situation causing the change of temperature change and thus the actual current value, such as a disconnection fault or short-circuit fault occurs.

[0023] In contrast, when determining that the average current in step S7 is not in the allowable range G _0, intended for a four-wheel all solenoids thus all of the shock absorber 6, and the duty ratio of the PWM output to 0% (4) The damping force of the shock absorbers 6 of all four wheels is extended so as to exhibit a hard / shrinkable software, so that the running stability is improved.

As described above, when the average current is compared with the current (estimated current) obtained based on FIG. 4 and it is determined that the average current is not within the allowable range G ₀ (the range determined by the estimated current), Set the duty ratio of PWM output to 0%,
The damping force of the shock absorbers 6 of all the wheels increases,
Present shrinking software. In the prior art, the magnitude of the damping force of only the shock absorber on the wheel side corresponding to the failed part is set to the safe side (for example, the extension side hard / retraction side software), and the running stability is impaired. In contrast, all four shock absorbers 6
Since the damping force of the vehicle is extended to exhibit a hard / shrinkable software, the stability of the entire vehicle is maintained and the running stability is ensured.

Further, at the time of a disconnection fault or a short-circuit fault, the average current is different from the estimated current. By comparing the average current with the estimated current as described above, it is possible to determine whether a disconnection fault or a short-circuit fault has occurred. In addition, when a disconnection failure or a short-circuit failure occurs, a failure determination is made, so that the damping force of the shock absorbers 6 of all four wheels is extended to exhibit hard / shrinkage software, thereby ensuring running stability. In addition, since the running stability can be ensured as described above in the case of a disconnection fault or a short-circuit fault without providing the monitor circuit used in the conventional technology, the size and cost of the device can be reduced because the monitor circuit is not provided. Becomes possible.

Next, a second embodiment of the present invention will be described with reference to FIGS. The second embodiment is different from the first embodiment in that a step S7A (solenoid current feedback process) is provided instead of step S7, and a step S8A (solenoid current limiting process) is provided instead of step S8. The main difference is that the temperature of the solenoid is estimated in steps S7A and S8A, and the command current is adjusted (restricted) according to the estimated temperature.

The processing contents of steps S7A and S8A will be described below. First, the solenoid current feedback subroutine of step S7A will be described with reference to FIG. This solenoid current feedback is performed by an interrupt operation executed every half a dither cycle. In FIG. 8, first, it is determined whether or not the rising flag is 1 (step S21). Step S21
If YES is determined (up flag = 1), A / D conversion of the down current (current at the down duty ratio) is performed to obtain the actual current at the down time (step S22). Step S2
If NO is determined in step 1 (rising flag # 1), the actual current is obtained by performing A / D conversion of the rising current (current at the rising duty ratio) (step S23).

Following the processing in steps S22 and S23, an average current (actual current, energizing current) is calculated from the rising current and the falling current obtained in steps S22 and S23 (step S24). Step S25 following Step S24
And the amount of change in battery voltage (battery voltage correction coefficient) K
_{Find V.} Following step S25, the command current (estimated current), it calculates a temperature correction coefficient K _T from the average current and the battery voltage correction coefficient K _V (step S26). Next, FIG.
With obtaining the reference duty ratio from the map shown in, it calculates the corrected reference duty ratio by multiplying the battery voltage correction factor K _V and the temperature correction coefficient K _T in the reference duty ratio (step S27).

Thereafter, in step S28, the rising flag is set to 1
Is determined. If YES is determined in step S28 (up flag = 1), the up duty ratio is calculated based on the corrected reference duty ratio and the map of FIG. 4 (step S29), and the up flag is cleared (step S30). On the other hand, if NO is determined in the step S28, the falling duty ratio is calculated based on the corrected reference duty ratio and the map of FIG. 4 (step S31), and the rising flag is set (step S32). Then, step S29
By outputting a PWM signal having the rising duty ratio calculated in step S31 and the falling duty ratio calculated in step S31, a current including a dither current as shown in FIG. .

Next, the solenoid current limiting subroutine of step S8A will be described with reference to FIGS. In the solenoid current limiting subroutine (FIG. 9), a calculation process is performed as described later based on the correspondence between the current (actual current) flowing through the solenoid and the temperature of the solenoid, for example, as shown in FIG. Here, FIG.
Prior to the description of the processing contents, basic items including FIG. 10 will be described.

FIG. 10 shows the relationship between the current flowing through the solenoid and the temperature of the solenoid. As shown in FIG. 10, the current decreases as the temperature rises. For example, if the current is I ₁ when the temperature is 20 ° C., the temperature becomes 2
When 0 becomes higher temperature T ₂ than ° C., current is I ₁ is smaller than I _2. When the current changes in accordance with the temperature change, the temperature correction coefficient in step S26 also changes, and the relationship between the temperature correction coefficient and the temperature is, for example, as shown in FIG.

A memory (not shown) stores a map indicating the correspondence between the maximum output current (current limit value) and the temperature as shown in FIG. The maximum output current is the current energizing the solenoid can be tolerated, up to a predetermined temperature (if shown in FIG. 12 T _1), the value is constant, in the case shown in the temperature T ₁ ~ allowable maximum temperature (FIG. 12, 100 ℃)
Then, the value becomes smaller as the temperature rises.

In the solenoid current limiting subroutine (FIG. 9), a corresponding temperature (estimated temperature) is calculated from the map of FIG. 11 using the temperature correction coefficient calculated in step S26 as an address (step S41). Next, step S41
The maximum output current (current limit value) is determined from the estimated temperature calculated in step (1) and the data in FIG. 12 (step S42).

Subsequent to step S42, the aforementioned steps
It is determined whether the command current (estimated current) obtained in S5 is larger than the maximum output current calculated in step S41 (step S43). If NO is determined in the step S43, the process returns to the main routine and is performed. On the other hand, if YES in step S43, that is, if it is determined that the command current is larger than the maximum output current, the duty ratio is corrected and the command current is set to the maximum output current (step S44). For example, the step
When not performing the current limit processing at S44, the output current is compared to can exceed the maximum output current I _M is as shown by reference numeral R ₁ in FIG. 13, the current limit in step S44 becomes an output current shown by symbol R ₂ by executing the process, it does not exceed the maximum output current I _M. Therefore, a rise in temperature can be suppressed.

Since there is a correspondence relationship between the maximum output current to be compared in step S43 and the temperature as shown in FIG. 12, the comparison with the allowable temperature is made in the determination in step S43. ing. Then, determining that the command current is larger than the maximum output current corresponds to determining that the expected temperature of the solenoid is higher than the allowable temperature.

In the present embodiment, as described above, it is determined that the command current is larger than the maximum output current (step S4).
If the determination is YES in 3), that is, if it is determined that the expected solenoid temperature is higher than the allowable temperature, the command current is set to the maximum output current (step S44).
), The temperature of the solenoid can be kept within the allowable temperature. For this reason, according to the present embodiment, it is possible to prevent the occurrence of a short-circuit failure due to a rise in the temperature of the solenoid. In addition, it is also possible to combine the above embodiments.
This corresponds to steps S6 and S7 in FIG. 2 of the first embodiment.
Between the steps S7A and S7A shown in FIG.
S8A is provided.

[0037]

According to the first aspect of the present invention, the heat generation of the solenoid, and the average current of the energizing current which determines the temperature of the solenoid determined by this heat generation, become large due to a short-circuit failure or the like, and the response to the PWM signal. If the current deviates by more than a predetermined value compared to the estimated current obtained by
The control circuit sets the duty ratio so that the magnitude of the damping force of the shock absorber of each wheel is on the safe side in running the vehicle. Therefore, even if a short-circuit fault occurs, the stability of the entire vehicle is maintained, and the running stability is ensured. Also,
The running stability can be ensured as described above in the event of a short-circuit failure without providing the monitor circuit used in the prior art. Therefore, the size and cost of the device can be reduced because the monitor circuit is not provided. The invention according to claim 2 provides a PW
The temperature of the solenoid is estimated from the estimated current obtained in response to the M signal and the average current of the energizing current, and an allowable current value is obtained from the estimated temperature. If the average current exceeds the allowable current value, the average current is Since the duty ratio of the PWM signal is changed so as to decrease, the energizing current decreases. Therefore, even if a short circuit fault occurs and the temperature of the solenoid rises, the temperature rise of the solenoid can be suppressed to a predetermined value or less.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a suspension control device according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a main routine of the controller of FIG. 1;

FIG. 3 is a flowchart showing a solenoid driving subroutine of FIG. 2;

FIG. 4 is a diagram showing a duty ratio-average current characteristic of the device of FIG. 1;

FIG. 5 is a diagram showing an energizing current including dither oscillation obtained by the apparatus of FIG.

FIG. 6 is a diagram showing a duty ratio-current characteristic of the device of FIG. 1 using a voltage value and a temperature as parameters.

FIG. 7 is a flowchart illustrating a main routine of the controller according to the second embodiment of this invention.

FIG. 8 is a flowchart showing a solenoid current feedback subroutine of FIG. 7;

FIG. 9 is a flowchart showing a solenoid current limiting subroutine of FIG. 7;

FIG. 10 is a diagram showing temperature-current characteristics.

FIG. 11 is a diagram showing a temperature-temperature correction coefficient characteristic.

FIG. 12 is a diagram showing a temperature-maximum output current characteristic.

FIG. 13 is a diagram showing a comparison of output current characteristics when the current is limited and when it is not.

FIG. 14 is a diagram schematically showing an example of a conventional technique.

[Explanation of symbols]

 2 Solenoid 5 Proportional solenoid valve 6 Shock absorber 8 Controller 12 CPU

Claims (2)

[Claims] 1. A solenoid connected to a power supply via a PWM signal generating means for generating a PWM signal having a variable duty ratio, a switching means for turning on and off in response to the PWM signal, and a displacement corresponding to a current supplied to the solenoid. A proportional solenoid valve having a movable body that moves, a shock absorber of a variable damping force type that is interposed between a vehicle body and an axle of each wheel so as to extend and contract to generate a damping force according to the displacement of the movable body; A control circuit that obtains the energizing current including dither vibration by switching a duty ratio of a PWM signal at predetermined time intervals, wherein the control circuit detects an average current of the energizing current, If the average current deviates by a predetermined value or more compared to the estimated current obtained in response to the PWM signal, Suspension control system, characterized in that the magnitude of the damping force of the click absorber to set the duty ratio to a predetermined value. 2. A solenoid which is connected to a power supply via a PWM signal generating means having a variable duty ratio for generating a PWM signal, and a switching means which is turned on and off in response to the PWM signal, and is displaced in accordance with a current supplied to the solenoid. A proportional solenoid valve having a movable body that moves, a shock absorber of a variable damping force type that is interposed between a vehicle body and an axle of each wheel so as to extend and contract to generate a damping force according to the displacement of the movable body; A suspension control device for obtaining said energizing current including dither vibration by switching a duty ratio of a PWM signal at predetermined time intervals, wherein an average current of said energizing current is detected and said PWM
Estimating the temperature of the solenoid from the estimated current and the average current determined in response to the signal, determining an allowable current value from the estimated temperature, and determining the average current if the average current exceeds the allowable current value. The PWM so that
A suspension control device for changing a duty ratio of a signal.